Creating threads
June 18th, 2009I struggled with this concept for a while so thought I would write a little post about it.
Is it possible to create a multi-threaded application in Visual C++ Express, which lacks ATL and MFC library support.
The answer is yes, you use the CreateThread API call and here’s how:
Make sure these headers are included:
#include <windows.h>
#include <stdio.h>
Now create your thread function, this function is what gets executed by the CreateThread API call. In my example I want to pass an object to the thread and then do something with it. In my case I am invoking my objects load function.
DWORD WINAPI LoadObject(LPVOID lpParameter)
{
MyObjectType* f;
f = (MyObjectType *) lpParameter;
f->load();
return 0;
}
Now we’re ready to create our thread from within our main code…
DWORD dwThreadId;
HANDLE hThread = CreateThread(
NULL, // pointer to security attributes
0, // initial thread stack size
LoadObject, // pointer to thread function
(LPVOID)&f, // argument for new thread
0, // creation flags (immediate)
&dwThreadId // pointer to receive thread ID
);
if (NULL == hThread) {
// error reporting here
exit(1);
}
// for example purposes, wait for the thread to complete and each second until it does print a '.' to the console.
while(TRUE) {
if (WaitForSingleObject(hThread, 1000)==WAIT_OBJECT_0) break;
printf(".");
}
// You then need to close your handle to the thread with
CloseHandle(hThread);
// That's it, obviously a very simple example and you will want to be creating multiple threads simultaniously etc.